In the Bible, it is a word that is used to tell the reader to stop and think about what was just read or sung.
It is a word that is used in religious writings, so it is usually thought of as serious and important.
Examples:
In the song, it says 'selahs' after the words about being happy.
The book of songs has 'selahs' in it.
When I read the old book, I see 'selahs' a lot.
The man says 'selahs' after he reads the old words.
The old book has 'selahs' after every sentence.
I see 'selahs' in the book, and I stop to think about what I read.